Operant visual learning and memory

In Drosophila, MBs seem especially involved in olfactory learning and memory and not in visual learning (Wolf et al. 1998). Flies can remember that a visual pattern represents a danger because this cue has been associated with heat (for review, see Heisenberg et al. 2001). Recently, using a variety of neurogenetic tools, Liu et al. (2006) identified a central brain structure, the fan-shaped body (FB), as being involved in visual memory (Fig. 4). After showing that the adenylate-cyclase Rut was required for the association between the visual pattern and the reinforcer, they restored a normal

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Fig. 4. Schematic representation of mushroom bodies (MB) and Central Complex (CX) neuropile. Dorsal is up; the most anterior is the first plane. MB: y lobes, striped; a and p lobes; a' and p' lobes; ped, peduncle; Ca, calyx; CX: EB, ellipsoid body; FB, fan-shaped body; NO, nodulli; PB, protocerebral bridge

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Ventral

Dotso ' j Caudal

Fig. 4. Schematic representation of mushroom bodies (MB) and Central Complex (CX) neuropile. Dorsal is up; the most anterior is the first plane. MB: y lobes, striped; a and p lobes; a' and p' lobes; ped, peduncle; Ca, calyx; CX: EB, ellipsoid body; FB, fan-shaped body; NO, nodulli; PB, protocerebral bridge visual memory capacity in the rut mutant by specifically expressing the rut gene in the upper stratum of the FB (called the F5 neurons). Interestingly, F5 neurons are required to learn about the horizontal elevation of a cue, whereas the ability to learn about the contour orientation of the pattern involves FB F1 neurons (a lower horizontal stratum in FB). These results suggest that memories of two different visual features - elevation in the panorama and contour orientation - are stored in different groups of neurons within the same structure (Liu et al. 2006).

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